JPH03245758A - Brushless motor - Google Patents

Abstract

PURPOSE:To facilitate manufacture of a stator winding by approximately equalizing the shape of a junctioned narrow magnetic pole and an auxiliary projecting piece to the shape of a wide magnetic pole, and winding stator windings, respectively, around a first coupling iron core and a second coupling iron core being separated in the diametrical direction. CONSTITUTION:A first coupling iron core 25a magnetically couples the center of a wide magnetic pole 23, formed in the shape to become approximately symmetrical in front and rear in the rotational direction of a permanent magnet rotor 10, with a yoke 31, and on it a stator winding 21 is wound, and a second coupling iron core 25b is provided at the position which makes an angle of 180 deg. in the rotational direction of the permanent magnet rotor to the first coupling iron core 25a, and magnetically couples one end of a narrow magnetic pole 24 with the yoke 31, and on it a stator winding 21 is wound. An auxiliary projecting piece 26 is coupled on the side of one end of the narrow magnetic pole 24, and is arranged along the periphery of the permanent rotor 10, and the shape of the jointed narrow magnetic pole 24 and the auxiliary projecting piece 26 is approximated to the shape of the wide magnetic pole 26.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a brushless motor driven by a 5DC power source.

[Conventional technology]

Conventionally, this type of brushless motor has been provided in which a permanent magnet rotor rotates around the outer periphery of a stator. For example, a combination of a permanent magnet rotor 10 magnetized as shown in FIG. 6(a) and a stator 20 having salient magnetic poles as shown in FIG. 6(b) is used. Are known. Further, a magnetically sensitive element (not shown) is disposed at a fixed position facing the magnetic poles of the permanent magnet rotor 1o, and detects the polarity of the permanent magnet rotor 10 passing through. The stator 20 has four main poles 22a arranged at equal intervals and wound with 1,000 fixed turns m21, and auxiliary poles 22b provided between adjacent main poles 22a. Stator winding 21
are provided as a pair, and the energization timing is set according to the polarity detected by the magnetically sensitive element. The permanent magnet rotor 10 also includes a first magnetized section 10a that has four poles magnetized at equal intervals in the rotation direction, and a second magnetized section 10b that has eight poles magnetized at equal intervals in the rotation direction. are doing. With such a configuration, as shown in FIG. 4, the waveform of the reluctance torque T2 when the stator 20 is not energized has a period twice that of the waveform of the basic torque T1 when the stator is energized. By ensuring that the resultant torque is always positive and eliminating dead centers, self-starting is possible. In the above configuration, although self-starting is possible, the permanent magnet rotor 1
Since the magnetization form of 0 is complicated and magnetization is not easy, and the stator 20 requires an auxiliary pole 22b in addition to the main pole 22a, the stator 20 also has a complicated shape and is difficult to manufacture. The problem was that it was not easy. Further, since the auxiliary pole 22b is required in addition to the main pole 22a, there is a problem in that the weight increases and weight reduction cannot be achieved. As a configuration in which the permanent magnet rotor 10 is easily magnetized and the auxiliary poles are removed from the stator 20, the configuration shown in FIG. 7 can be considered. In this configuration, the permanent magnet rotor 10 and the stator 20 each have two poles, and instead of providing auxiliary poles,
A wide magnetic pole 23 whose width at the part facing the permanent magnet rotor 10 is a wide width D1 and a narrow width D2 (1/2 D 1≦D2≦
A narrow magnetic pole 24 with a width of 1/3 D, ) is provided, and the center lines of the wide magnetic pole 23 and the narrow magnetic pole 24 are arranged to be deviated by 25 to 45 degrees from a position of 180 degrees in electrical angle. This is what we are doing. With such a configuration as well, the basic torque T and reluctance torque T2 having waveforms as shown in FIG. 4 can be obtained. Therefore, it is possible to obtain a brushless motor in which the resultant torque is always positive and is capable of self-starting without a dead center.

[Problem to be solved by the invention]

The structure shown in FIG. 7 has the advantage that the magnetization form of the permanent magnet rotor 10 is simplified and the shape of the stator 20 is simplified, which facilitates manufacturing and leads to weight reduction. However, the narrow magnetic pole 24 is different from the wide magnetic pole 23.
are deviated from the equidistant positions, the interval between the wide magnetic poles 23 and the narrow magnetic poles 24 is narrower than when they are equidistant, and the winding space for the stator winding 21 is restricted. It turns out. In addition, since the distance between the wide magnetic pole 23 and the narrow magnetic pole 24 is narrow, the insulation distance between each stator winding 21 wound around the wide magnetic pole 23 and the narrow magnetic pole 24 is shortened, and both stator windings There may be cases where sufficient insulation between the parts 21 cannot be obtained. Furthermore, if the distance between the wide magnetic pole 23 and the narrow magnetic pole 24 is narrow, there is also the problem that it becomes difficult to wind the stator winding 21. Furthermore, in both configurations of FIG. 6 and the seventh cause,
Since the permanent cornerstone rotor 10 is configured to rotate outside the stator 20, the proportion of the stator winding 21 in the total volume (i.e., the space factor) is relatively small, and a large torque can be obtained. If so, the overall diameter would become larger. For example, in a hair dryer with a comb, etc., the diameter of the housing must be 30 to 40 feet because the part of the housing that houses the motor is held.
If a conventional brushless motor were to be used to obtain the necessary torque, the diameter would be approximately 60 mm, making it difficult to use. In addition, grinders for dentists and small grinders for microprocessing machines are often held like pens, so it is desirable that they have a diameter of 16+v or less, and they also need to be able to obtain an output of about IOW. However, it was difficult to obtain high output with a small diameter. moreover,
It is desirable for these motors to have a rotational speed of 110,000 rpm or more, but in a configuration where the permanent magnet rotor 10 rotates outside the stator 20, it is difficult to maintain dynamic balance and the moment of inertia becomes large. , it was difficult to rotate at high speed. The present invention aims to solve the above-mentioned problems, and it is relatively easy to wind the stator winding, easy to manufacture, lightweight, and has a large space factor of the fixed winding. It is an object of the present invention to provide a brushless motor which can be made small in diameter, has easy dynamic balance, and can be rotated at high speed.

[Means for Solving the Problems 1] In order to achieve the above object, the present invention provides a two-pole permanent magnet rotor in which different magnetic poles are magnetized at equal intervals in the rotational direction, and a permanent magnet rotor with two poles magnetized at equal intervals in the rotational direction. The stator has one wide magnetic pole and one narrow magnetic pole facing the surface, and the polarity of the magnetic poles of the permanent magnet rotor that is fixed in a fixed position facing the magnetized surface of the permanent magnet rotor and passes through is detected. A stator is provided with a magnetically sensitive element and a current switching circuit that energizes the stator winding so that the polarity of the wide magnetic pole and the narrow magnetic pole is alternately switched in accordance with the polarity detected by the magnetically sensitive element, A stator is created by magnetically coupling a yoke disposed to surround the outer periphery of a permanent magnet rotor and the yoke to the center of a wide magnetic pole formed in a shape that is approximately symmetrical from front to back in the rotation direction of the permanent magnet rotor. A first connecting iron core around which a winding is wound, and a yoke and one end of a narrow ia pole provided at a position making 180 degrees in the rotational direction of the permanent magnet rotor with respect to the first connecting iron core. and a second connecting iron core on which the stator windings are wound, and a second connecting iron core that is magnetically coupled to the first end of the narrow magnetic pole in the rotational direction of the permanent magnet rotor, and is coupled along the outer circumferential surface of the permanent magnet rotor. An auxiliary protrusion made of a non-magnetic material is provided, and the shape of the narrow magnetic pole and the auxiliary protrusion is made almost equal to the shape of the wide magnetic pole. [Function] According to the above configuration, since the stator windings are respectively wound around the first connecting iron core and the second connecting iron core which are spaced apart in the diametrical direction, the pair of stator windings This allows for a large distance between the stator windings, relatively easy winding of the stator winding, and ease of manufacturing, as well as a large insulation distance. Furthermore, the structure is such that the weight can be reduced by eliminating the need for auxiliary poles, and by increasing the space factor of the stator windings, the structure can be made high in torque and compact. Furthermore, by configuring the permanent magnet rotor to rotate inside the stator, the moment of inertia of the rotating part is reduced, and dynamic balance is easily maintained, allowing high-speed rotation.

【Example】

As shown in FIGS. 1 and 2, a permanent magnet rotor 10
is a cylindrical permanent magnet magnetized into two poles at equal intervals in the rotation direction, and the rotation shaft 11 is inserted through the rotation center. The stator 20 is disposed so as to surround the outer periphery of the permanent magnet rotor 10, and stator windings 21 are wound around important parts of the stator 20. That is, the iron core of the stator 20 is formed into a cylindrical shape by laminating thin sheets of silicon steel plates or amorphous steel plates, and the first connecting iron core 25a and Second connecting iron cores 25b are integrally provided, and the stator winding 21 is wound around each connecting iron core 25a, 25b by bifilar winding. The center portion of the wide magnetic pole 23 is integrally connected to the tip of the first connecting iron core 25a, and one end portion of the narrow magnetic pole 24 is integrally connected to the tip of the second connecting iron core 25b. Further, an auxiliary protrusion 26 made of a non-magnetic material is coupled to the one end side of the narrow magnetic pole 24. Further, the shape of the narrow magnetic pole 24 and the auxiliary protruding piece 26 combined is almost the same as the shape of the wide magnetic pole 23. Therefore, both connecting iron cores 25a. Each stator winding 21 wound around 25b can be formed to have the same number of turns. That is, the auxiliary protrusion 26
By forming these, the winding space of the stator winding 21 with respect to both connecting iron cores 25a, 25b becomes equal, and since both connecting iron cores 25a, 25b are ME in the diametrical direction, the winding space becomes equal. As a result, the winding work of the stator winding 21 becomes easier. Furthermore, since the stator winding 21 is disposed outside the permanent magnet rotor 1o, the stator winding 21 is disposed outside the permanent magnet rotor 1o. 1 Wide magnetic pole 23 and narrow magnetic pole 24 and are opposed to the outer circumferential surface of the permanent magnet rotor 10 with an appropriate gap therebetween. Here, the area of the narrow magnetic pole 23 facing the permanent magnet rotor 10 is 172 to 1/3 that of the wide magnetic pole 24.
It is formed so that The stator 1 is disposed in close contact with the inner peripheral surface of a yoke 31 that is formed into a cylindrical shape and serves as an outer shell. Both end surfaces of the yoke 31 are bearing bases 32a, respectively. 32b. A coupling recess 33 is formed in the bearing bases 32a and 32b, and by caulking the coupling pieces 34 formed at both ends of the yoke 31 into the coupling recess 33, the bearing base is attached to the yoke 31. 32a and 32b are fixed. Each bearing base 32a, 32
Bearings 35, which are oil-impregnated bearings made of sintered alloy or the like, are held at the center of b, and both ends of the rotating shaft 11 are rotatably supported by each bearing 35, respectively. Further, a terminal plate 36 made of a printed circuit board is attached to one of the bearing bases 32a, and is arranged so that the polarity of the magnetic poles of the permanent magnet rotor 10 can be detected at a position facing the magnetic pole surface of the permanent magnet rotor 10. Lead wires of the provided magnetically sensitive element 37 such as a Hall IC are connected to the terminal board 36 . Next, the operation will be explained. Now, the width D1 of the wide magnetic pole 23 is assumed to be 150 degrees in electrical angle, and the width of the narrow magnetic pole 24 is assumed to be 90 degrees in electrical angle. Since the magnetic flux generated from the permanent magnet rotor 10 is constant, the concentration of magnetic flux on the narrow magnetic pole 24 is higher than that on the wide magnetic pole 23, and the attractive force between it and the permanent magnet rotor 10 is , the narrow magnetic pole 24 is larger than the wide magnetic pole 23. That is, in the non-excited state,
The permanent magnet rotor 10 is shown in FIG. 3(a) with respect to the stator 20.
It will stop at the position. Therefore, the center position of the magnetic pole facing the wide magnetic pole 23 in the permanent magnet rotor 10 is shifted from the center position of the wide magnetic pole 23. From this state, as shown in FIG. 3(b), the wide magnetic pole 2
When the fixed prewinding M21 is energized so that 3 is the N pole and the narrow magnetic pole 24 is the S pole, the permanent magnet rotor 10 is rotated to the right by the repulsive force between the N pole of the permanent magnet rotor 10 and the wide magnetic pole 23. It will rotate around. In other words, self-starting becomes possible. Thereafter, the permanent magnet rotor 10 is rotated as shown in FIG.
When it rotates to state e), the polarity detected by the magnetically sensitive element 37 is reversed, so the direction of energization of the stator winding 21 is switched so that the excitation polarity of the wide magnetic pole 23 and the narrow magnetic pole 24 is reversed. That is, the current is applied so that the wide magnetic pole 23 becomes the S pole. As a result, the permanent magnet rotor 1
A repulsive force acts between the permanent magnet rotor 10 and the stator 20, and the permanent magnet rotor 10 continues to rotate. Furthermore, the state shown in FIG. 3(d) is passed and the state shown in FIG. 3(b) is returned again, and the rotation of the permanent magnet rotor 10 is continued. The basic torque T during excitation and the reluctance torque T2 during non-excitation have a relationship as shown in FIG. 4, and the resultant torque is always positive, making self-start possible. To explain in more detail, the wide magnetic pole 23 is set to approximately 150 degrees in electrical angle, and the narrow magnetic pole 24 is set to approximately 90 degrees in electrical angle. The center position of the second connecting iron core 25b
This corresponds to a position offset by about 45 degrees from the center line of Therefore, the reluctance torque T2 becomes maximum at the positions of π and 2π of the basic torque T1, and the resultant torque does not become zero. θ1 in FIG. θ2
indicates a position where the permanent magnet rotor 10 stably stops. θ corresponds to the position in FIG. 3(1). Note that since the permanent magnet rotor 10 is in a fixed position when not energized, the torque at startup is also constant. Here, in the third factor, the north pole of the permanent magnet rotor 10 faces the wide magnetic pole 23 during non-excitation, but the same is true when the south pole faces the wide magnetic pole 23. Switching of the current direction to the stator winding 21 based on the output of the magnetically sensitive element 37 is performed by a current switching circuit as shown in FIG. The stator winding 21 includes each connecting iron core 25a,
25b is continuously wound by bifilar winding, and each line is a separate coil L3. L
2. In the position shown in FIG. 3(b), the magnetically sensitive element 37 detects the north pole of the permanent magnet rotor 10, and in this position outputs a signal to turn on the transistor Q. The constants of resistors R1 to R3 are set so that when transistor Q is on, transistor Q is on and transistor Q2 is off. When transistor Q is on, wide magnetic pole 23 is turned to N pole by coil L1. If the connection relationship is set so that the permanent magnet rotor 10 rotates from the state shown in FIG. When a pole is detected, transistor Q is turned off, transistor Q1 is turned off, transistor Q2 is turned off,
is turned on. At this time, the coil L2 is energized, so if the connection is set so that the wide magnetic pole 23 becomes the S pole due to the coil L2, the permanent magnet rotor 10 will rotate from the state shown in FIG. 3(c). It turns out. In this way, each coil L1 forming the stator winding 21 is determined according to the polarity detected by the magnetically sensitive element 37.
By switching the energization state to Lz, the permanent magnet rotor 10 can be kept rotating. According to the above configuration, the diameter of the rotating part is small and the moment of inertia is small, so it is easy to maintain dynamic balance.
For example, it is possible to obtain a very high rotation speed of 50,000 rpm by reducing the diameter of the permanent magnet rotor 10 to 10 zm or less. In addition, as described above, the space factor of the stator winding 21 can be increased, and high output can be obtained despite the small size.
It is also possible to obtain high output such as IOW with a small diameter of z. Therefore, a motor suitable for hair dryers, small grinders, etc. can be obtained.

【Effect of the invention】

As described above, the present invention includes a two-pole permanent magnet rotor in which different magnetic poles are magnetized at equal intervals in the rotation direction, and one wide magnetic pole and one narrow magnetic pole facing the magnetized surface of the permanent magnet rotor. A stator having each pole, a magnetically sensitive element that is fixed at a fixed position facing the magnetized surface of the permanent magnet rotor and detects the polarity of the magnetic pole of the passing permanent magnet rotor, and the polarity detected by the magnetically sensitive element. A current switching circuit that energizes the stator windings is provided so that the polarity of wide magnetic poles and narrow magnetic poles is alternately switched according to the current. a first connecting iron core around which a stator winding is wound, the yoke magnetically coupling the yoke to the center part of a wide magnetic pole formed in a shape that is approximately symmetrical in the front and rear directions in the rotational direction of the permanent magnet rotor; and a first connecting iron core, which is provided at a position making 180 degrees in the rotational direction of the permanent magnet rotor with respect to the first connecting iron core, magnetically couples one end of the narrow magnetic pole to the yoke, and is wound with a stator winding. 2
and an auxiliary protrusion made of a non-magnetic material that is connected to the one end side of the narrow magnetic pole in the rotation direction of the permanent magnet rotor and arranged along the outer peripheral surface of the permanent magnet rotor. , the combined shape of the narrow magnetic pole and the auxiliary protrusion is approximately equal to the shape of the wide magnetic pole, and the first connecting iron core and the second connecting iron core separated in the diametrical direction each have Since the stator windings are wound, the distance between a pair of stator windings can be increased, making it relatively easy to wind the stator windings, making it easier to manufacture, and improving insulation. It has the advantage of being able to cover a large distance. Furthermore, the structure is such that the weight can be reduced by eliminating the need for auxiliary poles, and by increasing the space factor of the stator windings, the structure can be made high in torque and compact. moreover,
Since the permanent magnet rotor is configured to rotate inside the stator, the moment of inertia of the rotating part is reduced, dynamic balance is easily maintained, and high speed rotation is possible.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a vertical sectional view and a horizontal sectional view showing an embodiment of the present invention, FIG. 2 is an exploded perspective view of the same, and FIG. 3 is an exploded perspective view of the same.
4 and 4 are operation explanatory diagrams of the same as above, FIG. 5 is a circuit diagram showing an example of a current switching circuit used in the above, and FIG. 6 (,) is a perspective view showing an example of a conventional permanent magnet rotor. Figure 6 (b
) is a plan view showing an example of a conventional stator, and Fig. 7 (1) (
b) is a vertical cross-sectional view and a horizontal cross-sectional view of another conventional example, respectively. 10... Permanent magnet rotor, 20... Stator, 21...
... Stator winding, 23... Wide magnetic pole, 24... Narrow magnetic pole, 25a... First connecting iron core, 25b... Second
connecting iron core, 26-... auxiliary protrusion, 31... yoke,
37--Magnetic sensing element.

Claims (1)

[Claims] (1) A stationary device equipped with a two-pole permanent magnet rotor with different magnetic poles magnetized at equal intervals in the rotational direction, and one wide magnetic pole and one narrow magnetic pole, each facing the magnetized surface of the permanent magnet rotor. With a child
A magnetic sensing element is fixed at a fixed position facing the magnetized surface of the permanent magnet rotor and detects the polarity of the magnetic pole of the passing permanent magnet rotor. The stator is equipped with a current switching circuit that energizes the stator windings so that the polarity with the magnetic poles is alternately switched.
A yoke arranged around the outer periphery of the permanent magnet rotor,
A first connecting iron core magnetically couples a yoke to the center part of a wide magnetic pole formed in a shape that is substantially symmetrical in the front and rear directions in the rotational direction of the permanent magnet rotor, and a first connecting iron core around which a stator winding is wound; A second connecting iron is provided at a position making 180 degrees in the rotational direction of the permanent magnet rotor with respect to the connecting iron core, magnetically couples one end of the narrow magnetic pole to the yoke, and is wound with a stator winding. The core includes a core, and an auxiliary protrusion made of a non-magnetic material that is connected to the one end side of the narrow magnetic pole in the rotation direction of the permanent magnet rotor and is disposed along the outer peripheral surface of the permanent magnet rotor. A brushless motor characterized in that the shape of a combination of a narrow magnetic pole and an auxiliary protrusion is approximately equal to the shape of a wide magnetic pole.